Seeing a Micron
The following images are of a penny under different magnifications to show you how small a micron is. I chose a penny because everyone knows how small they are, has seen one and has actually held one in there own hand. The image below is the back of a penny using a digital camera.
The back of a modern penny showing the Lincoln Memorial.
Have you ever noticed that the Abraham Lincoln can actually be seen in his Memorial on the back of a penny? The next six images were collected using the scanning electron microscope in SED mode. The yellow number in the upper right corner of each image is a scale in microns. The text below each image describes what you are looking for.
This image is at 26 times magnification (or 26x) and shows a nice image of Lincoln in the Memorial.
At 100x we see a closer view of Lincoln with his head in the center. Notice the speck of dust to the left of the head.
At 500x the speck of dust is now a rock and it is difficult to see Lincoln. We can now see surface details on the penny.
At 2500x the dust particle is getting too big to work with, so we will concentrate on the surface defect to the lower left of it. You can just see this surface defect in the previous image as well.
At 10000x the surface defect fills the screen.
At 25000x the surface defect is too large to fit in the image. A measurement reveals that the defect is less that one half of a micron wide.
The magnification of 25000x is about as far as our SEM can go without the images getting too blurry to be useful, but it is more than enough for Gunshot Residue Anaslysis.